The proposed work will involve studies of the ability of preformed chemotactic factor to induce inflammatory reactions in the lung following instillation into the tracheo-bronchial tree. These reactions will be monitored quantitatively by measurements of vasopermeability changes and leukocyte influx. We will also continue to pursue the regulation of leukotactic factors by products of blood leukocytes and alveolar macrophages. Finally, the interaction of chemotactic factors with leukocytes, resulting in cell aggregation, will be assessed, particularly with reference to cationic requirements.